Absolute-pressure gauge



'C. H. BERRY.

ABSOLUTE PRESSURE GAUGE. APPLICATION min 050. i0, 1920.

1,414,854. Patented y 2, 1922.

110M211: as Munulm' 3144mm Cfifirold Derry ae fi-wp riser .l aide" r. 3%. ll has? ABSOLUTE-PRESSURE GAUGE.

Specification or letters Patent.

Patented Mav a, rose.

Original application filed May 12, 1920, Serial No. 380,879. Divided and this application filed December To all whom it may concern:

Be it known that 1, CHARLES HAROLD BERRY, a citizen of the United States, residing at 368 Clarendon Avenue, Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Absolute-Pressure Gauges, of which the following is a specification, reference being had therein to the accompanying drawings.

This application is a division of my copendin application Serial Number 880,879, filed ay 12, 1920, and is intended to embrace claims founded upon the manual setting of the compensating mechanism in contradistinction to the automatic setting thereof under the influence of a barometer.

In the accompanying drawing:

Figure 1 is a view of the gauge constructed in accordance with the invention with the casing of the gauge in section and with the pointer and its distinctions in elevation; and

Fig. 2 is a reduced face view of the dial of the gauge.

Referring to the drawing it will be seen that the casing 5 houses a pressure actuated element 6, which may be a Bourdon tube; said tube receiving pressure through a block 7 that is provided wlth a connection 8, in the usual and well known way. The tube 6 carries a head 10 to which one end of a link 11 is pivoted at 12. The other end of this link is pivoted at 13 to a floating lever 1a. The link 11 preferably includes a turnbuckle 15 in its length, which servesa purpose hereinafter set forth. One end of the floating lever 14 is connected by a pivot 16, with a tail extension 17 of an arcuate rack 18. This rack meshes with a pinion 19 that is fast upon the shaft 20 ofpointer 21.

The pointer 21 moves over the face of the dial 22 and coacts with a scale in the usual and well known way. The end of the floating lever 14 remote from the tail extension 17 is connected by a link 24; with an arm 25 of a bell crank lever 26 which has a pivotal mounting at 27.

The compensatory action which is the primary object of the present invention is efi'ected by moving the bell crank lever 26 in accordance with variations in atmospheric pressure. This movement is effected by means of a screw 28 that is threaded into a bearing 29 of the case. This screw has a, preferably, knurled head 30 located or Serial No. 429,734.

termined by the reading of a separate ba rometer; the resultant movement imparted to the arcuate rack 18 wlll act upon the pointer 21 to a sufiicient degree to compen sate for any change lIlfllJHlOSPllGllC pressure;

which may have taken place. since the previous settingv of the pointer 33.

In order that the reason for providing the compensatory action set forth may be fully appreciated, it is pointed out that practically all of the gauges in use at the present timeare constructed in such manner as to indicate pressures above and below atmospheric pressure, as a datum. In other words, the

' zero points of the said gauges correspond to atmospheric pressure instead of correspond.- ingto a complete vacuum. However, since the atmospheric pressure constantly varies, it is manifest that such gauges cannot accurately represent the true absolute pressure existing in the space to which the gauge is connected, because such space has no connection with the atmosphere, and the pressure therein prevailing does not vary with the atmospheric pressure. Therefore, in order to produce'a gauge that will be entirely accurate, I so construct the same that the Zero point thereof corresponds to a true vacuum and provide, in conjunction with the pointer actuating means consisting of the Bourdon tube 11, floating lever 14-, and arcuate rack 18 the means herein shown and described consisting of a link 2%, bell crank 26 and the actuating means therefor, which serve to so modify the action of the pointer actuating means as to compensate for variations in atmospheric pressure and to cause the resultant reading of the gauge to indicate the true absolute pressure, without computation, at any given time. Under present conditions, if it is desired to determine an accurate value of the absolute pressure from an ordinary type of gauge, it is necessary to read both the guage and the barome er,

' rometer reading.

It is manifest that the dials may be graduated in many different ways in accordance with the work that the gauge is called upon to do. The pressures may be indicated in any units whatever, English, metric or any other, and incorrespondence with the pres sure scales, there maybe scales of the temperature of vaporization of any substance or scales of any other quantity which varies with and depends upon the temperature, such, for example, as scales of the density of saturated vapor, of total heat or the like.

The pointer 33 serves the function of inclicating to the operator when the screw 30 has been turned enough to effect the compensatory action, this point being reached when the pointer 33 indicates upon the scale 84 the then prevailing atmospheric pressure.

As is well known Bourdon tube gauges gradually shift their Zero point with age and sustained pressure. The method commonly employed for correcting this is to remove the pointer from the stem and press it on again in a new position, so that the gauge registers correctly. The provision of the turnbuckle l5 renders it possible to calibrate the gauge without removing the pointer.

It is to be understood that the invention is not limited to the precise construction set forth but that it includes within its purview whatever changes fairly come within eithen the terms or the spirit of the appended claims.

Having described my invention, what I claim is:

1. A gauge comprising a dial, a pressure actuated element, a pointer operable over the dial, connections between the pressure actuated element and the pointer for moving the pointer in accordance with the movements of said pressure actuated element and manually operable settable means for modifying the action of the first named connections upon the pointer to compensate for variations in atmospheric pressure.

2. A gauge comprising a dial, a pressure actuated element, a pointer operable over the dial, connections between the pressure actuated, element and the pointer for shifting the pointer in accordance with movements of said element, said connections including a pivoted member and manually operable means for shifting the fulcrum of said pivoted member to thereby modify the action of the said connections upon the pointer to compensate for variations of atmospheric pressure.

3. A structure as recited in claim 2 wherein the manually operable means includes a pointer and a barometric scale upon the face of the dial over which said pointer moves.

l. A structure as recited in claim 2 wherein the manually operable mechanism com prises a pivoted bell crank lever, a link connecting one end of said bell crank lever with and forming the pivotal mounting for said pivoted element, a manually operable screw engaging the opposite end of the bell crank lever, a pointer mounted at the pivot point of the bell crank lever and a barometric scale upon the dial with which said pointer cooperates.

5. A gauge comprising a dial, a pointer operable thereover, there being a pressure scale upon the dial the zero point of which corresponds to a true vacuum and there being a barometric scale upon the dial, a pressure actuated member, connections between said member and the pointer including an arcuate rack, a floating lever pivotally connected to the arcuate rack, a connection between the pressure actuated member and the floating lever, a pivoted lever, a manually operable screw for adjusting the position of the same, aconnection between said pivoted lever and the floating lever and a pointer movable with said pivoted lever and coacting with the barometric scale of the dial.

In testimony whereof I hereunto afiix my signature.

0. HAROLD BERRY. 

